898 
GENETIC AND BIOLOGICAL EFFECTS OF RADIATION 
20. Moon, H. W., Stoner, R. D., Joel, D. D., Chanana, 
A. D., and Cronkite, E. P. Response of lymphocyte- 
depleted calves to fluid tetanus toxoid. Am. J. Vet. 
Res. 29:1211, 1968. 
21. McGregor, D. D., and Gowans, J. L. The antibody 
response of rats depleted of lymphocytes by chronic 
drainage from the thoracic duct. J. Exptl. Med. 
117:303, 1963. 
22. Chanana, A. D., Brecher, G., Cronkite, E. P., 
Joel, D. D., and Schnappauf, H. The influence of 
extracorporeal irradiation of the blood and lymph 
upon skin homograft rejection. Rad. Res. 27:330, 
1966. 
23. Chanana, A. D., Chonkite, E. P., Joel, D. D., and 
Schiffer, L. M. Skin allograft survival in calves. 
Influence of thymectomy and extracorporeal irradi- 
ation of blood. Arch. Surg. 98:803, 1969. 
24. Joel, D. D., Chanana, A. D., Cronkite, E. P., and 
Schiffer, L. M. Modification of skin allograft im- 
munity by extracorporeal irradiation of lymph. 
Transplantation 5:1192, 1967. 
25. Chanana, A. D., Cronkite, E. P., Joel, D. D., and 
Stevens, J. B. Prolonged renal allograft survival: 
Extracorporeal irradiation of blood. Transplanta- 
tion Proc. 3:838, 1971. 
26. Cottier, H., Schindler, R., Burki, H., Sordat, B., 
Joel, D. D. and Hess, M. W. Kinetic aspects of 
lymphocyte recirculation. Intern. Arch. Allergy 
Appl. Immunol. 41:4, 1971. 
27. Jansen, C. R., Cronkite, E. P., Mather, G. C, 
Nielsen, N., Rai, K. R., Adamink, E. R., and Sipe, 
C. R. Studies on lymphocytes. II. The production 
of lymphocytosis by intravenous heparin in calves. 
Blood 20:443, 1962. 
28. Weeke, E., and Sorensen, S. F. Extracorporeal 
irradiation of the blood: Lymphocyte trans- 
formation tests and clinical results after renal 
transplantation. Transplantation Proc. 3:387, 1971. 
DISCUSSION 
Frank P. Hungate, Battelle Pacific North- 
west Labs : Do you have evidence concerning the 
persistence or dose-related effect on those cells 
w^hich are initially nondividing? In other vi^ords, 
do you have any evidence that the small dose 
given twenty times has more or less effect than 
a large second dose given later? 
Dr. Joel: We don't have this type of infor- 
mation with respect to lymphoid cells, unfor- 
tunately, because these are difficult to keep in 
the blood stream and we don't know how many 
transits they make. We do have good data with 
respect to cells which do stay in the blood, 
namely red cells. I can't answer your question 
with respect to cells that would divide after- 
wards. We do see chromosome aberrations. 
We haven't followed them for long periods of 
time, but we do see them in lymphoid cell pop- 
ulations. Pm sure that, in any given population 
of cells which makes a transit through the radi- 
ator, there are bound to be some cells which 
will survive, irrespective of the dose, even if 
you went to extremely high doses. But what the 
chances are of these surviving long enough to 
not have left the blood, to make another transit, 
we don't know. 
